An avionic equipment unit of the aforementioned type is known from document FR 2 933 557 A1. This document describes a mechanism for protecting the integrity of data transmitted over a network using the AFDX technology in the aeronautic field. A detection of an absence of alteration of the data transmitted between transmitting equipment and receiving equipment is done via a cyclic redundancy check (CRC).
The transmitting equipment then encodes the data to be transmitted, by implementing a predefined rule, the calculated code for example being based on a particular CRC, different from the CRC according to standard IEEE 802.3. The transmitting equipment then associates the calculated code with the data, and transmits, to the receiving equipment, a message including the data and the associated calculated code, the code being an integrity code associated with the data. The receiving equipment then implements said predefined rule on the received data and verifies whether the integrity code thus obtained is equal to the integrity code included in the received message, a difference between these two integrity codes indicating the presence of an alteration of the transmitted data.
Document FR 2 871 012 B1 also describes the use of a cyclic redundancy check in the context of loading applications toward servers on board an airborne means of transportation. A sent message then comprises a secure header including an integrity check field for the data contained in the secure header, for example in the form of a cyclic redundancy code (CRC), calculated from a list of files present in a corresponding part of the header. The integrity check field then allows the recipient of the secure header to verify that the data received in this header indeed complies with what was sent.
However, the protection of the transmitted data is not optimal with such an avionic equipment unit.